[Fordim Hedgethistle]

This is what you will find under "religion" in the Oxford English Dictionary:

1. a. A state of life bound by monastic vows; the condition of one who is a member of a religious order, esp. in the Roman Catholic Church.

b. man, etc. of religion, one bound by monastic vows or in holy orders. Obs.

c. house, etc. of religion, a religious house, a monastery or nunnery. Obs.

2. a. A particular monastic or religious order or rule; a religious house. Now rare.

b. collect. People of religion. Obs.

c. A member of a religious order. Obs.

3. a. Action or conduct indicating a belief in, reverence for, and desire to please, a divine ruling power; the exercise or practice of rites or observances implying this. Also pl., religious rites. Now rare, exc. as implied in 5.

b. A religious duty or obligation. Obs.

4. a. A particular system of faith and worship.

b. the Religion [after F.]: the Reformed Religion, Protestantism. Obs.

c. religion of nature: the worship of Nature in place of a more formal system of religious belief.

5. a. Recognition on the part of man of some higher unseen power as having control of his destiny, and as being entitled to obedience, reverence, and worship; the general mental and moral attitude resulting from this belief, with reference to its effect upon the individual or the community; personal or general acceptance of this feeling as a standard of spiritual and practical life.

b. to get religion: see GET v. 12d.

c. Awe, dread. Obs. rare1.

6. transf. a. Devotion to some principle; strict fidelity or faithfulness; conscientiousness; pious affection or attachment. Obs.

b. In phr. to make (a) religion of or to make (it) religion to, to make a point of, to be scrupulously careful (not) to do something.

7. The religious sanction or obligation of an oath, etc. Obs.

8. attrib. and Comb., as religion-complex, -dresser, -game, -making, -mender, -monger, -shop; religion-arousing, -infectious, -masked, -raptured adjs.; religion man = sense 1b.

Of all these the only sense in which I think we can claim that Tolkien has 'founded' a religion would be number 6 insofar as many people (and I'd posit everyone here) approach Tolkien's writings very much in that way: "Devotion to some principle; strict fidelity or faithfulness; conscientiousness; pious affection or attachment." But this definition depends upon the act of the reader and not of the writer at all -- Tolkien's world and vision has been made into a 'kind' of religion (and only in the loosest sense) by others....

So you see, it really is all up to the reader after all!